Fractional flow reserve, quantitative flow ratio, and instantaneous wave-free ratio: a comparison of the procedure-related dose of ionising radiation

Diagnostic performance of quantitative flow ratio in non-ST elevation acute coronary syndromes in comparison to non-hyperemic pressure ratios: a prospective study

Quantitative flow ratio (QFR) is a new angiography-based coronary physiology tool aimed to evaluate functional relevance of intermediate coronary lesions. Aim of the study is to assess diagnostic performance of QFR in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) in comparison to currently used non-hyperaemic pressure ratios (NHPRs). In this prospective, single-centre study, coronary physiology of intermediate coronary stenoses of non-culprit vessels in patients presenting with NSTE-ACS was evaluated using NHPRs (iFR, DFR or RFR). Subsequently, QFR was computed offline by a QFR analyst blinded to the NHPR results. Diagnostic performance of QFR was assessed in comparison to NHPRs as reference standard. A total of 60 vessels with intermediate coronary stenoses was investigated. The NHPRs were used as follows: RFR 38%, DFR 47% and iFR 15% of the cases. The NHPR result was positive, showing significant lesion, in 19 cases. A significant correlation was found between NHPR and QFR (r = 0.84, p < 0.001). Classification agreement of the two methods (95%) and diagnostic performance of QFR in comparison to NHPR (AUC: 0.962 [0.914-1.00]) were both high. Sensitivity, specificity, positive and negative predictive value of QFR in comparison to NHPR were 84.2%, 100%, 100% and 93.2% respectively. QFR has high diagnostic performance in detecting functionally significant lesions of non-culprit arteries in patients with NSTE-ACS and multivessel disease. Due to its high negative predictive value, it can be used to safely avoid unnecessary invasive physiological assessment of these lesions.

Comparison of FFR, iFR, and QFR assessment in patients with severe aortic stenosis and coronary heart disease

Introduction

Some patients with coronary heart disease are diagnosed with severe aortic stenosis. For further treatment, coronary angiography is performed in these patients. For intermediate lesions, obtaining coronary artery physiological data can facilitate clinical decision-making regarding revascularization.

Aim

The study compared the physiological significance of coronary artery stenosis using the fractional flow reserve (FFR) method with instantaneous wave-free pressure ratio (iFR) and quantitative flow ratio (QFR) in patients qualified for aortic valve replacement.

Material and methods

Data were collected on patients hospitalized in the years 2019–2020 at the 2^nd Department of Cardiology, University Hospital in Krakow.

Results

Twelve patients with severe aortic stenosis and borderline lesions in the coronary artery were qualified for physiological assessment. There were 6 women, whose mean age was 73.8 ±7.5 years. The mean left ventricular ejection fraction was 52 ±15%. The mean aortic valve area was 0.80 ±0.16 cm². The left anterior descending artery was assessed in 12 from 13 cases (92%). In comparison to FFR, all iFR measurements were concordant with FFR. The total agreement between QFR and FFR/iFR assessment was 69%.

Conclusions

Despite the controversy and uncertainty of some operators regarding the interpretation of the FFR test in patients with severe aortic stenosis, we obtained complete agreement of FFR with iFR assessment. This fact suggests that in patients with severe aortic stenosis the choice of an invasive method to assess the physiological significance of the stenosis in the coronary artery is not crucial – both iFR and FFR allow comparable results.